Manufacture of cellulose derivative materials



Jan. 3, 19329. H. DREYFUS AL 2,142,722

' MANUFACTURE oF -cELLuLosE DERIVATIVE MATERIALS v original Filed Feb. 1, 1935 J: A h

Patented Jan; a, 1939 MaNUrAc'rcnaor clamorosa naalva'rlva m'rrmts Henry Dreyfus-,'Londom and Robert Wighton Moncrleif and Frank Brentnall Hill, Spondon, near Derby, England, aasignors to Celanese Corporation ot America, a corporation of Deiaorlginai application February 1,1935, serial No. 4,510.' Divided and vthis application January 30,1193?, Serial N0. 123,104.' In Great Britain February 2,v 1934- 1.o claims. (ci. a-iziz)A This invention relates to new processes for the production of artiicial filaments, threads, yarns,

ribbons, Yfoils-Elms and other materialsv having a basis of cellulose acetate or other cellulose ester or ether and having improved properties, particularly improved tensile/strength.

This application is a divisional application of our application Serial No. 4,510, filed Feb. 1, 1935. i The production of lmaterials oi the above character, and particularly filamentsv and similar textile materials, having an increased tensile strength is of considerable importance from the commercial point of view. The processes which have been hitherto proposed with this object have involved subjecting the threads vor othermaterials to a stretching operation,- and in order to obtain substantial increases in tensile strength it has' been considered necessary to 'subject thematerials to the action of liquids which are solvents or swellingv agents for the materials, for

example dioxane, acetone, acetic acid, and diacetone alcohol, all applied for example inl aqueous solution. It has also been suggested' to use such liquids in the vapour state.

It has now been discovered that thetensile strength of materials having a basis of. cellulose acetate or other cellulose ester or ether may be increased in a very simple manner by subjecting them to a stretching operation in the presence of saturated or wet steam under pressure at a temperature above C. Besides being cheap and easy from the manipulative point of view, the new process has the advantage over the prior processes that it is considerably more ex-` ible. Thus, in processes in which aqueous dioxane or aqueous acetone is employed .as the agent facilitating the stretching of cellulose de-' rivative threads, relatively minor changes in the conditions, particularly the .temperature and concentration, may have a profound effect upon the properties of the stretched threads, and accordingly to obtain a uniform .product it is essential to maintain' the conditions constant withinvery fine limits. With the new process the range of toleranceismuch greater.

By the new process'a degree of stretch for example, 200% and even many hundreds per cent., may be obtained.r Thus apart'from increased tensile strength, the new process enables laments or threads of A fine denier and thin foils, nlms and the llike to be produced.

The steam is employed under pressure and the materials may thus be subjected to relatively high temperatures while maintaining the steam in the saturated or wet condition. Thus, for instance,l the steam may be at a temperature of 120, 130 or135" C. or moreandat-the appropriate pressure for the steam to be saturated or wet, such as 10, 20, 30 pounds or more per square inch above atmospheric pressure. The best conditions for treatment are dependent upon the degree of stretch required and the rate of stretching and upon a numbervof factors to be referred to hereinafter. For relatively lowv degrees of stretch the pressure may be quitelow, e. g. only a few pounds above atmospheric pressure, the temperature being preferably so ad- .justed that at the pressure chosen the steam is only just saturated or slightly wet.

The steam may bebrought into the saturated or wet condition by any suitable means. If superi heated steam be used as the source of supply, then cooling, for example by radiation, may be resorted to, to secure the required conditions, or' water may be injected into the steam so as to produce both `a cooling and the presence of fliquid water. The steam may be generatedin situ in the stretching chamber.

Textile materials to be treated inl accordance with the invention may be threads or other materials composed of continuous filaments, or may be spun yarnsfmade of short or more or less long lengths of filament, and may be obtained by cutting up or by any other suitable process, for exampleby the processes of U. S. Patent No; 2,077,078. The materials may initially have any desired lustre from a high lustre to medium lustre or approximately the lustre of natural silk or even a dull lustre orno lustre at all. Thus,

the materials may have a low lustre pdue to the presence therein of titanium dioxide or other pigments. Preferably 'the materials on entering the steam are substantially free from volatile solvents.`

The operation may be carried out on the materials in anyjsuitable form; for example threads may be stretched in hank form, for instance between rollers positioned in a vessel containing steam. Preferably, however, stretching of the materials 1s effected during the course of their travel from one point to another. The treatment may be applied to a single thread, e. g. during winding from a cake or cheese or bobbin onto a bobbin, or it may be applied to a number of 'threads-simultaneously. Thus, threads maybe stretched while running from one creel of bobblns ,to another creel. When simultaneously stretching a, number of threads, it is advantageous to arrange the threads in parallel alignment in the tei-mediate, rollers or other. stretching devicesv may be provided so as to carry put the stretch in more lthan one stage.

Apparatus enabling the stretching to be carried out is described and claimed in our co-pending application No.' 48,084. Broadly the apparatus comprises a steam chamber, means for creating `an'atmosphere of steam therein and means for stretching the materials while-in the chamber. Preferably the steam is introduced from outside the chamber. For the treatment of running threads or other materials, the .new apparatus comprises a steam chamber provided with means for introducing steam and one or more inlet and outlet orices for the materials, assoelated with means for stretching the materials while in the chamber. Preferably the means for introducing the steam into the chamber are such as to direct steam jets on to the materials immediately upon entry into the steam chamber. 'I'he steam chamber'may be provided with a pressureess of the invention is illustrated in the accompanying drawing in which Fig. 1 illustrates the general lay-out of the apparatus, the steam chamber being shown in `longitudinal section: and

" -a pipe I3 through a reducing valve il.

.2 illustrates a cross-section of the ste chamber on the line 2 2 of Fig. 1.

A number of threads I drawn from a creel of bobbins y2 is carried through'suitable nip rollers 3 positioned in front of a steam box or pipe l. v'I'he threads are drawn through the steam box or pipe by means of nip rollers 5 positioned at the far end of the steam box or pipe, and finally are taken up on a creel of bobbins 6. 'I o the ends of the steam boxor pipe 4 are secured closure plates'l and l bored with the appropriate holes the 'steam may be quite short and good stretching may be obtained with a length of only a fewinches. However. it is preferable to extend the length of the lsteam chamber to some feet, for example 3-6 feet or more, the precise length depending upon the temperature and the amount and rate of stretching.

- As previously indicated, for any particular degree of stretch and rate of stretching, a range o f temperatures and therefore steam pressuresA is available. The best temperature at which to work depends upon a large number of factors. including the twist on the initial thread which for quick stretching should be as small as possible, the nature of the cellulose derivative under treatment, materials made of high viscosity cellulose their extensibility.

derivatives requiring in general rather higher temperatures and therefore pressures than materials made of Alow viscosity cellulose derivatives, and the size of the inlet and outlet orifices, and also the position of the steam jets in the steam chamber in relation to thev incoming materials. As previously indicated, the inlet and outlet holes are sumciently s'mall to enable the pressure to be maintained. Their size may be varied with the denier of the threads undergoing stretching. Generally, subject to variation by the above factors,l the higher degrees of stretch or higher rates of stretching require higher temperatures and therefore higher pressures of the steam.

'I'he temperature and therefore the pressure of lacter where it is desired. On the other hand,

where, as is desirable in most cases, the individual iilamentary character of the threads is to be preserved. simple adjustments in the pressure, rate of stretching, amount of stretching, size of inlet and outlet orices, and the various other factors readily enable this to be done.

The stretched materials may be subjected to any desired after-treatment processes. Thus, the filaments, threads, foils, films and the like may be treated with shrinking agents to improve Suitable processes forthis purpose are described in U. S. Patent No. 2,058,422. In particular reference is made to the latent solvents referred to in that specification, for example a mixture of methylene chloride and benzene.

Again, stretched cellulose ester materials mayv be subjected to processes of saponiiication. The saponiilcation may be such as to lead to a relatively small loss in weight, for example sulcient to give the materials an aiiinity for cotton dyestus, or may be complete or substantially complete, i. e. so as to eliminate all or substantially all of the ester content. The saponiiication may be eiIected under such conditions of tension that shrinkage takes place during or immediately after the saponiiication, this being advantageous from the point of view of the extensibility of the products.

such further treatments may be earned out as l operations separate from the stretching or may be carried out continuously with stretching. Thus for example, the invention includes a continuousoperation which involves ilrst stretching and then shrinking, for example a stretching to several hundreds per cent. of the original length of the material followed by a shrinking by 'I12% .may be stretched by the processes described and in the case of foils, films and the like the stretchvent lateral shrinkage' during the application of a longitudinal stretch. l

What we claim and desire to secure by Letters VPatent isz- 1. Process for improving the strength of filaments, threads and similar textile materials and of foils, lms and the like made of an organic substitution-derivative of cellulose, which comprises stretching the materials in wet steam under pressure at a temperature above C.

2. Process for the production'of lustrous laments, threads and similar textile materials and of foils, illms and the like made of an organic substitution derivative of cellulose, which materials have an improved tenacity which comprises stretching Vthe materials to a ,degree greater than the dry extensibility thereof in wet steam under pressure at a temperature be'- tween 100 C. and 110 C. during their travel from one point to another.

3. Process for improving the strength of lilaments, threads and similar textile materials and of foils, films and the like made of cellulose acetate, which comprises stretching the materials to a degree greater than the dry extensibility thereof in wet steam under pressure at a under pressure at a temperatureiof C. to

C. during their travel from one point to another. 4 1

5. Process for improving the vstrength of laments,` threads and similar textile materials and oi' f oils, lms and the like made of Vcellulose acetate, which comprises stretching the materials to a degree greater than the dry extensibility thereof in Wet steam under pressure at a temperature of 110 C. to 125 C. during their travel from one point to another.

6. Process for improving the strength of iliaments, threads and similar textile materials and of foils, lms and the like made of cellulose acetate, which comprises stretching the materials to .a degree greater than the dry extensibility thereof in wet steam under pressure at a temperature above 125 C. during their travel from one point to another.

7. Process for improving the strength of laments, threads and similar textile materials made of cellulose acetate, which comprisesl stretching the materials to at least 200% of their original length in Wet steam under pressure at a temperature between 100 C. and 110 C. during their travel from one point to another.

8. Process for improving the strengthof laments, threads and similar textile materials made of an organic substitution derivative of cellulose, which comprises stretching the ma-A terials to at least 200% of their original length in wet `steam under pressure at a temperature of 110 to. 125 C. during their travel from one point to another.

9. Process for improving the strength of laments, threads and similar textile materials made of cellulose acetate, which comprises stretching the materials to at least 200% of theiroriginal length in wet steampnder pressure a-t a tem',-

perature of 110 C. to 125 C. during their travel from one point to another. Y

10. Process for improving the strength of laments, threads and similar textile Amaterials made of cellulose acetate, which comprises stretching the materials to at least 200% o! their original length in wet steam under pressure at a temperature above 125 C. during their travel from one point to another.

' HENRY DREYFUS.

ROBERT wrGH'roN MoNcRrEFF. 

